JP2551590B2 - Speed control method for copier optical system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a speed control method for an optical system in an optical movable copying machine.

[Prior art]

Generally, in an optical system movable copying machine, a document is exposed at a constant speed when the optical system feeds, and is returned to the home position at a high speed when returning. The higher the return speed, the more preferable, but the higher the return speed, the more difficult it is to stop the optical system at a predetermined position.
There is also a method of increasing the return speed and decelerating and stopping by using a clutch, a brake or the like, but it is not possible to realize a smooth return operation due to a large mechanical shock. In addition, this method also requires repair work due to mechanical wear, resulting in high maintenance costs.

There is also a technology proposed to set the initial speed to R1 at high speed on return, and switch to R2 at low speed when approaching home position to shorten the return time as a whole. It becomes impossible to shift from R1 to R2 at. Therefore, the value of R1 cannot be set so large that the actual return could not be shortened.

〔Purpose〕

The present invention has been made based on such a background, and an object of the present invention is to provide a speed control method for an optical system capable of increasing the return speed and accurately controlling the stop position. It is in. It is another object of the present invention to provide a speed control method for a digital control device to perform speed control with no speed deviation with respect to a target speed of an optical system of a copying machine, even if a load changes.

〔Constitution〕

Therefore, according to the present invention, when the optical system of the copying machine is returned, the electric motor is controlled so as to reach the preset target speed when the preset first braking start position is reached, and the optical system of the copying machine controls the target speed. When the speed becomes lower than the speed, the state quantity of the target speed in the steady state is set as a new initial value in the microcomputer, and the electric motor is controlled so as to reach the target speed. When the control start position is reached, the control is released to shift to the stop mode.

An embodiment of the speed control method for the optical system of the copying machine according to the present invention will be described below.

In FIG. 1, reference numeral 1 is a microcomputer including a microprocessor 2, a read only memory (ROM).
3. Tandem access memory (RAM) 4 is connected via BUS. Reference numeral 5 denotes a command generation circuit that outputs a status command signal that commands the status of the electric motor 8, and generates a speed command signal and the like. The output of this command generation circuit 5 is also connected to BUS. Reference numeral 10 denotes a detection interface circuit that processes the output of the incremental encoder 9 and converts it into a digital value, and includes a counter that counts the output pulse of the incremental encoder 9. Reference numeral 6 is a driving interface circuit, which converts the digital value of the calculation result of the microcomputer 1 into a pulse-shaped signal (control signal) for operating a power semiconductor constituting the driving circuit 7, for example, a transistor. The drive circuit 7 operates based on the pulse-shaped signal and controls the voltage applied to the electric motor 8.

As a result, the electric motor 8 rotates at a desired speed. The rotation speed of the electric motor 8 is detected by the incremental encoder 9 and the interface circuit 10 and taken into the microcomputer 1. Reference numeral 11 denotes an optical system of the copying machine attached to the electric motor 8. Also, the interface circuit 10
Determines the rotation direction of the electric motor 8 and a home position sensor HPS described later.

FIG. 3 is a perspective view of an essential part of the optical system 11 of the copying machine.
In the optical system 11, the optical system scanning unit 31 that scans a document is a light source.
Mirror base that integrates 31a and two mirrors 31b and 31c
Mirror 31 that reflects the reflected light from MB1 and the original to mirror 31b
It consists of a mirror base MB2 that supports d. These mirror bases MB1 and MB2 are horizontally slidably supported by two rails 32 and 33. One side portion 34 of the mirror base MB1 is fixed to the wire 35, and both of the mirror bases MB1 and MB2 are moved to A in accordance with the movement of the wire 35 in the A or B direction.
Direction (feed direction), B direction (return direction). The wire 35 is wound around the pulleys 36 and 37 and the rotating shaft of the electric motor 8, and follows the forward and reverse rotations of the electric motor 8 to form a mirror base.
MB1 and MB2 are designed to reciprocate.

The side 34 for fixing the wire of the mirror base MB1 has a vertical piece 34a, and the vertical piece 34a is provided in the stop area of the mirror base MB1.
A home position sensor HPS that detects a is arranged. The stop region of the mirror base MB1 is a range from when the rear end portion C of the vertical piece 34a cuts the optical path of the home position sensor HPS to when it moves in the B direction (return direction) by about 10 mm. The position where the rear end portion C of the vertical piece 34a has moved by about 10 mm after passing the set position of the home position sensor HPS is the mirror base MB1, that is, the stop position of the optical system.

Next, an optimum reguulator calculation method in which there is no output deviation from the target value calculated by the microcomputer 1 will be described.

The equation of state when the inductance L of the DC motor is small and can be ignored is given by equation (1).

ω; Motor speed; ω differential value K _T ; Motor torque constant J; Motor and load inertia u; Motor input voltage Output equation is y = c · ω (2) c; Constant and discrete The state equation of the system is ω (k + 1) = pω (k) + qu (k) (3) The output equation is y (k) = cω (k) (4) p, q in the equation (3) It is a constant determined by the sampling time of.

FIG. 2 is a block diagram of the optimum reguulator control without deviation with respect to the target speed according to the present invention.

R (k) is a speed command for rotating the electric motor 8 at the target speed, and is determined by the value given by the command generation circuit 5 in FIG. y (k) is the speed converted into the digital value of the electric motor 8 detected by the interface circuit 10 in FIG. The speed detection method will be described later.
K0 and K1 are optimum gain vectors determined by solving the Riccati equation. Next, a method for obtaining the optimum gain vector will be described.

 The following equation of state is created from equations (3) and (4).

Here, s (k) = ω (k) −ω (k−1) (6) d (k) = u (k) −u (k−1) (7) In equation (5), far.

The weight matrix Wx is Becomes

As an evaluation when controlling the electric motor 8 J is used to obtain the control input d (k) that minimizes J. W is a non-negative weight factor.

The matrix Riccati formula is H (k + 1) = P1 ′ · H (k) · P1−P1 ′ · H (k) ·
Q1 (W + Q1 '・ H (k) ・ Q1') ^-1 Q1 '・ H (k) ・ P1 +
Wx (12) H (0) = Wx, k = 0,1,2 ... H (k) in the equation is a 2 × 2 symmetric matrix, and converges to a stable solution as the iterative calculation progresses. If the steady solution is H, then the optimum gain vector G = (K0, K1) is G = (W + Q1 ′ · H · Q1) ⁻¹ Q1 ′ · H · P1 …… (13) (12), (13) In the equation, P1 ′ and Q1 ′ are the transposed matrices of P1 and Q1 () ⁻¹ are the inverse matrices of (), and the optimal gain vectors K0 and K1 are obtained.

Next, a method for detecting the speed will be described. The processing method of the detection interface circuit 10 by processing the output of the incremental encoder 9 of FIG. 1 will be described. The detecting interface circuit 10 connects the output of the incremental encoder 9 to the interrupt of the microprocessor 2 and also has a counter for counting the reference clock (CLK).

Now, the state immediately before the edge (109) of FIG. 4 arrives will be described. 0B is an output pulse of the incremental encoder 9, and CLK is a reference clock of the detecting interface circuit. The counter executes the decrement count from the count number given, for example, 0FFFFH, with the pulse period of Tn−1 as the reference of the CLK signal. When the edge 109 reaches the interrupt of the microprocessor 2, the interrupt routine shown in FIG. 5 is started. Then, the decrement count value of the counter is latched in the storage register built in the detection interface circuit 10 by (P1). Next, the decrement count value latched by P2 is stored in the RAM 4 of FIG. Then, the count number 0FFFFH for counting the pulse period of Tn is given to the counter, the counter starts the decrement count from the initial value (0FFFFH) again, and ends the interrupt processing.
When the edge (110) arrives again, the above-mentioned processing is repeated.

 Further, the conversion of the speed ω (k) is given by the equation (14).

T _CLK ; CLK cycle N _E ; Incremental encoder division number n; CLK count number = 0FFFFH- Decrement count number k; Unit conversion constant to rotation speed K: Constant The above is the speed detection method using the interrupt.

FIG. 6 is an explanatory view showing the outline of the optical velocity control method in this embodiment.

The same figure shows the mirror base speed and the rotation speed of the electric motor 8 from the stop position of the mirror base MB1 to the feed, the return and the return to the stop position.

The mirror base MB1 is located at the stop position P at the time of initialization. When the electric motor 8 is driven in this state, it is accelerated in the feed direction, and the home position sensor HPS position Q
The stop area E up to the point is crossed and the image area is entered. The degree of acceleration is set to be large in proportion to the set magnification. The mirror base speed is stabilized when reaching the leading end position R of the image area, and the speed is controlled so as to be constant until reaching the end point S of the image area.

The stabilization of the mirror base speed in the image area is performed by the optimal regulator control algorithm described above.
In the figure, R10 to R12 indicate the motor rotation speed corresponding to the set magnification, and indicate that the mirror base speed in the image area is different corresponding to the set magnification. When the interface circuit 10 that counts the number of output pulses of the incremental encoder 9 detects that the mirror base MB1 has moved in the feed direction and has exceeded the terminal end S of the image area, the microcomputer 1 performs reverse braking. When the interface circuit 10 detects a V point at which the rotation direction changes from normal rotation to reverse rotation, optimal return control is performed so that the return speed becomes the maximum speed R1 which is considerably faster than the feed speeds R10 to R12. . maximum speed
When a certain distance L (braking start position A) is reached from point V at R1, optimum reguulator control is performed so that the target speed R2 is reached, and when the mirror base speed is below the target speed R2,
Optimal regulator control is performed by using the state quantity X0 in the steady state of the predetermined target speed R2 as a new initial value. The state quantity X0 is X0 in the block diagram of FIG. 2, but the steady state X0 can be obtained from FIG. 7 as a result of simulation. Seventh
In the figure, if target velocities R2, K _T , R, and J are given, optimal regu- lator control simulation can be performed, and the value of X0 becomes constant when the mirror base speed is stable, that is, in the steady state. The value may be given as the above-mentioned initial value. or,
If the target speed at feed is R2, RAM X4 at steady state X0
You may store it in and call it.

The speed R2 is the speed at which the mirror base MB1 can be accurately stopped at the stop position P when the sensor HPS position is changed to the motor braking state. The size of the speed R2 is set to an appropriate size in consideration of the stop region E, the maximum speed R1, and other various factors that affect the inertia.

When the sensor HPS position Q is reached at speed R2, the electric motor 8 is immediately braked in the reverse direction. After the reverse rotation braking for a predetermined time T _R , the electric motor 8 is turned off and stopped at the stop position P. The time T _R from the reverse braking to the X point at which the electric motor is switched off is large enough to accurately stop at the stop position P when the reverse braking is switched to the electric motor off. The predetermined time T _R is a time such that the electric motor 8 does not rotate in the feed direction.
The speed of the mirror base MB1 at this time is NL. Thus, reverse rotation braking is performed at the point Q, and reverse rotation braking is switched to the motor off at the point X, whereby the vehicle completely stops at the point P due to a slight inertia.

FIG. 7 shows the result of the simulation described above. It can be seen that the value of X0 is constant in the steady state.

FIG. 8 is a diagram for explaining the speed control method. Symbol P, Q,
S, U, A, X and HP correspond to the symbols in FIG.

From time O to point S, the feed control is performed by the optimum regulator. From point S to point A, high-speed control of return is performed by the optimum regulator. Speed from point A to point Q
Although the optimum regulator control is performed at R2, the control input U (k) is set to the + side up to point M because the speed decelerates rapidly.
The point M is when the rotation speed becomes less than R2, and optimal state control is performed with the state quantity X0 as a new initial value, so hunting does not occur and it quickly converges to the target value R2. . Until point Q performs optimal Regiyureta control at a rate of R2, performs plugging T _R period from the point Q, then OFF the motor was stopped.

FIG. 9 is a flow chart when the operation of FIG. 8 is executed by the microcomputer 1.

As described above, according to the present invention, since the transition from the maximum speed R1 to R2 at the time of return is performed by the reverse braking, it can be performed quickly, and when the speed becomes R2 or less (point M in FIG. 8). , The optimal reguulator control is performed with the state quantity X0 in the steady state as the initial value, so there is no vibration of the optical system and most of the inertial force can be absorbed, and there is almost no inertial force when shifting to the stop mode. be able to. For this reason, it is possible to accurately stop at the stop position, it is possible to perform smooth stop braking without needing to use a clutch or a brake, and it is possible to know the interval of the stop region. Can be realized.

〔effect〕

As described above, according to the present invention, (1) the return can be smoothly performed in a short time.

(2) Since the optimum reguulator control does not cause the deviation of the actual speed from the target speed, there is no need to perform PLL control and the circuit becomes simple.

(3) Since the feedback back gain and the state quantity are obtained by the simulation, there is no need to adjust the circuit or the program through experiments, which enables short-term development.

And so on.

[Brief description of drawings]

FIG. 1 is a speed control block diagram of an optical system of a copying machine according to an embodiment of the present invention, FIG. 2 is a block diagram of optimum reguulator control, and FIG. 3 is a perspective view of an essential part of an optical system of the copying machine. Fourth
FIG. 5 is a timing chart of the output pulse of the incremental encoder and the reference clock, FIG. 5 is a flow chart of its interrupt routine, FIG. 6 is a diagram showing an outline of an optical velocity control method according to the present invention, and FIG. 7 is a velocity control simulation. FIG. 8 is a diagram showing the results, FIG. 8 is a diagram for explaining the speed control method, and FIG. 9 is a flow chart when the operation of FIG. 8 is executed by the microcomputer. 1 ... Microcomputer, 5 ... Status command means, 7
...... Drive circuit, 8 ...... motor, 9 ...... speed detection means.

Claims (1)

(57) [Claims] 1. An optical system for a copying machine, an electric motor for driving the optical system for the copying machine, a means for driving the electric motor, a state commanding means for outputting a state command signal for instructing an operating state of the electric motor, and Speed control method for copier optical system having means for detecting speed of electric motor and microcomputer for inputting the state command signal and signal for detecting speed of the electric motor to calculate control signal to be given to the driving means At the time of return of the optical system of the copying machine, the electric motor is controlled so as to reach a preset target speed when the optical system of the copying machine reaches a preset first braking start position. Is lower than the target speed, the steady-state state quantity of the target speed is set as a new initial value in the microcomputer to set the target speed. The controls motor, when it came to the second braking start position set in advance as,
A method of controlling the speed of an optical system of a copying machine, wherein the control is released to shift to a stop mode.